Standard prior art valve seat inserts are press-fitted into and retained in an engine cylinder head by an interference fit of the insert with an opening in the head. A typical length for such an insert is at least 0.300 inches or 7.6 mm. For early industry needs such inserts provided an adequate performance. A recurring problem however is encountered by the industry for such inserts. That problem is how to reliably secure or lock the insert into the engine cylinder head so that it does not become dislodged during the operation of the engine.
An answer to that problem was developed by, and U.S. Pat. No. 4,236,495 issued to, Jose Rosan Jr. for a "Self-Locking Valve Seat Insert," on Dec. 2, 1980. What is shown and described in the patent to Rosan is a valve seat insert design which uses a serrated locking flange for achieving a reliable locking of the insert in the engine cylinder head. Such a solution has been widely received in the industry.
While the standard interference fit valve seat inserts and the Rosan self-locking valve seat insert provided early advances in the state of the art of the industry, such inserts have not necessarily kept pace with the engines in which they must be used. Specifically, as the state of the art for engines has steadily progressed, e.g. higher performance standards and the use of exotic materials for such engines, the transfer of heat in such engines has become a critical performance component. No longer is it merely satisfactory that a valve seat insert stay securely locked in the engine cylinder head, but such an insert must now contribute to achieving the optimum transfer of heat required by the new engine designs.
Hence the need for further development in the state of the art for valve seat inserts. It is believed the present invention advances the state of the art beyond what is presently known, to what is now needed to answer the new performance requirements of the next generation of internal combustion engine designs.